The present invention relates to incinerators in general, and more particularly to an incineration travelling grate of an incinerator, which grate comprises a plurality of axially parallel rollers rotated in a common direction and supporting refuse fed into the incinerator.
Roller or drum-shaped grates have been known in incinerators, particularly for burning solid refuse, such as house refuse. The refuse-supporting grate is formed of a plurality of drums positioned one after another in a descending manner and axially rotated in the same direction. Refuse is fed onto the uppermost drum and transported to the further drums due to their rotation while this refuse is burned.
Each drum is provided on its periphery with a plurality of grate bars positioned such that air slots for combustion air are formed therebetween. Combustion air is normally fed in the interior of the hollow drum and then is radially discharged through the air slots onto the fire space size. Combustion air at the same time serves as cooling air for the grate bars.
Generally, differently-formed grate bars have been utilized for covering the outer periphery of the grate drum. The predominant portion of the drum surface is formed by the grate bars suspended between respective grate bar carriers; the suspended grate bars being arrested in the segment-like manner with the fixed grate bars which are rigidly secured by screws to the bar carriers from the inner side of the drum.
In operation the grate bars are subjected to high loads and therefore to substantial wear, the magnitude of which significantly increases due to high temperatures. Furthermore, occasional mechanical damages by certain solid particles in a refuse are not avoided. Due to wear and damage therefore regular and also irregular interchanges of the grate bars have been required.
In addition, service-life of the grate bars are shortened considerably by metals melting at operating temperature, for example, alumina, zink, tin, contained in the refuse being incinerated. These metals melting during the incineration of refuse flow into the air slots between the grate bars, where they are cooled and solidified. Therefore caking takes place in the air slots, which caking gradually accumulates. If disturbances occur in the combustion air feeding system the clogged portion of the coating of the grate bar must be totally replaced.
The incineration grate of the type under discussion is disclosed in German patent publication DE-PS No. 11 64014. The grate is formed of grate drums provided with inserts through which drops of melted metal are collected in the interior of the drum. Thereby the clogging of the air slots on the side facing away from the combustion chamber is prevented.
U.S. Pat. No. 3,469,544 discloses a grate drum, the outer periphery of which is covered with grate bars of various different shapes. In addition to grate bars, the heads of which are toothed or wave-shaped, there are bars shown which have straight-line surfaces. There is no showing how the grate bars are secured to the drums and there are no spacers.